Haemopoiesis is the process by which cells in the blood become committed to a specific cell type, mature and proliferate. The production of blood cells is a dynamic and constant process and if dysregulated will result in a number of different diseases and-or leukemias. Using a leukemic cell line we identified two genes, Hls5 and Hls7-Mlf1, involved in red blood cell maturation. In addition, both these genes have been implicated in cancer, Hls5 functions as a tumor suppressor and Mlf1 is associat ....Haemopoiesis is the process by which cells in the blood become committed to a specific cell type, mature and proliferate. The production of blood cells is a dynamic and constant process and if dysregulated will result in a number of different diseases and-or leukemias. Using a leukemic cell line we identified two genes, Hls5 and Hls7-Mlf1, involved in red blood cell maturation. In addition, both these genes have been implicated in cancer, Hls5 functions as a tumor suppressor and Mlf1 is associated with acute myeloid leukemia. Over-expression of either gene in immature red blood cells inhibited their development; Mlf1 had quite a profound affect on cell shape and size whereas Hls5 affected biochemical pathways with a decrease in haemoglobin production. We have identified binding partners of each of the molecules. Hls5 binds to FOG 1, a regulator of the red blood cell genes. In addition, Hls5 associates with Ubc9 and PIAS-1 - molecules involved in a novel form of gene regulation called sumoylation. Hls5 also regulates GATA-1 a key protein in red cell production. Wer have recently found that Mlf1 also regulates GATA-1. Importantly, we have demonstrated that Mlf1 binds DNA and other nuclear proteins and is able to affect gene transcription. This project will use cellular and biochemical assays as well as mouse models to elucidate the mechanisms by which these genes control the function of red blood cells.Read moreRead less
DNA-binding proteins regulate gene expression and co-ordinate normal patterns of development. We are investigating a set of DNA-binding proteins, termed the Ikaros family. These proteins are known to be important regulators of white blood cell production and mutations that interfere with Ikaros activity are associated with aggressive childhood leukaemias that are resistant to treatment. Recently, it has become apparent that Ikaros proteins also regulate genes in red blood cells. One observation ....DNA-binding proteins regulate gene expression and co-ordinate normal patterns of development. We are investigating a set of DNA-binding proteins, termed the Ikaros family. These proteins are known to be important regulators of white blood cell production and mutations that interfere with Ikaros activity are associated with aggressive childhood leukaemias that are resistant to treatment. Recently, it has become apparent that Ikaros proteins also regulate genes in red blood cells. One observation is that Ikaros plays a role in silencing the foetal haemoglobin genes. The haemoglobin genes have been extensively studied because diseases, such as beta-thalassaemia, which are caused by mutations in the adult haemoglobin genes, are among the most common genetic diseases known. One strategy to alleviate beta-thalassaemia centres around re-activating the foetal globin genes and thereby re-supplying globin to adults who have only mutant forms. In this context, the observation that Ikaros plays a role in foetal globin silencing is of considerable medical significance. We have recently identified two new regulatory proteins that are related to Ikaros and are found in red blood cells. Little is known about these proteins but they can directly bind to Ikaros and they are capable of silencing gene expression. We therefore wish to test the hypothesis that they work together with Ikaros to silence gene expression. Ultimately we expect that understanding how these proteins and Ikaros operate will suggest new strategies for re-activating the silent foetal globin genes to treat beta-thalassaemia, as well as preventing the proliferation of white blood cells carrying mutant Ikaros proteins.Read moreRead less
Erythroid Molecular Cascades Involving The Tyrosine Kinase Lyn
Funder
National Health and Medical Research Council
Funding Amount
$496,500.00
Summary
Mature red and white cells develope from hemopoietic stem cells in the adult bone marrow. The production of red blood cells is primarily controlled by the hormone erythropoietin (Epo). The availability of this hormone in a recombinant form has aided in the treatment of numerous forms of anaemia resulting from kidney failure, malignancies, and AIDS. Previously we had identified that the protein Lyn must be present inside primitive red blood cells for Epo to stimulate them to become mature functio ....Mature red and white cells develope from hemopoietic stem cells in the adult bone marrow. The production of red blood cells is primarily controlled by the hormone erythropoietin (Epo). The availability of this hormone in a recombinant form has aided in the treatment of numerous forms of anaemia resulting from kidney failure, malignancies, and AIDS. Previously we had identified that the protein Lyn must be present inside primitive red blood cells for Epo to stimulate them to become mature functional cells. Recently, we have demonstrated that mice lacking the Lyn gene develope major problems with their red blood cells. We have identified several molecules which interact with Lyn in red blood cells. We have shown that a molecule called Cbp is important for Epo function in individual red blood cells and now we plan to investigate its function in whole animals. We have shown that a new molecule called Arp is important for red blood cell development. This protein moves in and out of the nucleus (where DNA is stored) and may be important in the regulation of genes needed for red blood cells. The third gene (AFAPbeta) is also novel and is closely related to another called AFAP-110, which can exert effects on the structure of a cell. Since red blood cells have to shrink considerably during their development, the role of AFAPbeta on red blood cell structure will also be investigated. From these experiments we should develop a much better understanding of how the production of red blood cells is controlled and how diseases of red blood cells (such as anaemia) occur.Read moreRead less